John Nash was an American mathematician who made significant contributions to the fields of game theory, differential geometry, and partial differential equations. He is best known for his work in game theory, for which he was awarded the Nobel Prize in Economics in 1994. Nash's life and career were the subject of the biographical film "A Beautiful Mind," which depicted his struggles with schizophrenia and his eventual recovery. Nash's work continues to have a lasting impact on various fields of mathematics and economics.